In the past, many valves of the gate, ball or plug types have employed sealing assemblies having seal rings composed of non-metallic resilient materials such as Nylon, Teflon, Kel-F, various elastomers and natural or synthetic rubber. Reference is made to U.S. Pat. Nos. 3,269,695 and 3,746,303. The latter patent discloses a valve mechanism having a sealing assembly with one part made of material such as Nylon and a second part made of a more resilient material such as synthetic rubber. The two parts are press fitted into an annular recess and provide finished sealing surfaces for engaging the valve working surface of a gate or other valve member. In one embodiment, the more resilient material is disposed adjacent one peripheral surface of the Nylon. In another embodiment, the more resilient material is disposed adjacent both the inner and outer peripheries of the Nylon.
Although the seat assemblies of the character set forth in the above identified patents have met with considerable success, in high pressure service conditions, they tend to be subject to pressure-induced seal erosion and are also subject to damage by pressure induced extrusion which tends to displace yieldable sealing material of the seat assemblies from their respective seal grooves to the extent that they can be damaged as the valve element is being moved between its open and closed positions. It is desirable, therefore, to provide a resilient face sealing assembly for the seat rings of valves which provides better seal adhesion than is normally available to thus provide more adequate retention of the sealing elements within the seal grooves, to resist pressure induced extrusion and erosion of the sealing members and to provide effective resistance to pressure induced seal blowout.
Many valve mechanisms are provided with seat assemblies having one or more springs that function to mechanically urge the seat assemblies toward sealing engagement with the working surface of the valve element. Typically, the seat rings are machined to provide multiple spring pockets with compression springs being located within the seat pockets to ensure that the springs are retained in evenly spaced relation about the periphery of the seat assembly. When the seat rings are disposed within their respective seat pockets within the valve body, the compression springs react against a spring stop surface or surfaces within the valve body and thus urge the seat ring into sealing engagement with the valve element. The formation of multiple spring pockets in a seat ring is an expensive manufacturing process and thus adversely affects the commercial feasibility of the resulting valve product. It is desirable, therefore, to provide means for adequate retention of multiple compression springs in appropriately retained, evenly spaced and guided relation with a seat ring while at the same time minimizing the manufacturing costs of the seat ring to thus enhance the commercial viability of the resulting valve mechanism.